Security tokens are used to authenticate or prove an identity of a user of a computer device. Sequence-based tokens generate a sequence of codes which can be used to add a layer of security to authentication procedures. Using security tokens adds a step to the user and device authentication process, which can include, for example, typing a code or inserting a smartcard. Authentication systems using security tokens, such as sequence-based tokens, can include prompting a user to enter a code retrieved from a hardware token device or software token application as part of the authentication process.